Power operator for a control valve

ABSTRACT

A power operator for a control valve capable of selective adjustment between an open and closed position to control pressure in a pipe line. The power operator includes a valve control shaft having a pair of radially extending crank arms which form an obtuse angle of approximately 90* and wherein one of the crank arms is slightly longer than the other crank arm. A hydraulic cylinder operator means is operatively associated with each of the crank arms, with the pair of hydraulic cylinder means being supported in substantially parallel relationship relative to each other. The pair of hydraulic cylinder means are connected to a hydraulic supply source whereby an input of hydraulic fluid to effect movement of one of the cylinder means in one direction will effect a simultaneous movement of the second cylinder in an opposite direction. A cam means is coaxially mounted on the valve control shaft and is operatively associated with a deceleration valve. The deceleration valve is connected in series with hydraulic flow of fluid between the hydraulic supply source and each of the cylinders. The valve control shaft cam means is detailed in design to control the speed of opening and closing of the valve, by the rotary position of the valve means.

United States Patent Phillips et a1.

[ Apr. 23, 1974 1 POWER OPERATOR FOR A CONTROL VALVE [75] Inventors: Raymond D. Phillips, Tucker Marshall U. Bagwell, Atlanta, both 211 App]. No.: 205,032

[52] US. Cl 251/62, 251/229, 91/18 C, 91/404, 91/410 [51] Int. Cl. FlSb 15/22, FOlb 1/00 [58] Field of Search 91/405, 404, 186, 406, 91/407, 408, 410; 92/68, 76, 140; 251/62 [5 6] References Cited UNITED STATES PATENTS 1,062,553 5/1913 Preston 91/404 1,980,374 11/1934 Bradshaw 91/404 .1 Primary Examiner-Paul E. Maslousky Attorney, Agent, or Firm-Newton, Hopkins &'

Ormsby 57 ABSTRACT A power operator. for a control valve capable of selective adjustment between an open and closedposition to control pressure in a pipe line. The power operator includes a valve control shaft having a pair of radially extending crank arms which form an obtuse angle of approximately 90 and wherein one of the crank arms is slightly longer-than the other crank arm. A hydraulic cylinder operator means is operatively associated with each of the crank arms, with the pair of hydraulic cylinder means being supported in substantially parallel relationship relative to each other. The pair of hydraulic cylinder means are connected to a hydraulic supply source whereby an input of hydraulic fluid to effect movement of one of the cylinder means in one direction will effect a simultaneous movement of the second cylinder in an opposite direction. A cam means is coaxially mounted on the valve control shaft and is operatively associated with a deceleration valve. The deceleration valve is connected in series with hydraulic flow of fluid between the hydraulic supply source and each of the cylinders. The valve control shaft cam means is detailed in design to control the speed of opening and closing of the valve, by the rotary position of the valve means.

11 Claims, 6 l )rawing Figures mm'rszmm 2 I914 SHEET 1 0F 2 77 Iii r10 '2 FIG 2A lh/km rops: PAM/0N0 0, Pym/p5 M /m U 546ml 514M #fl Q Jrraemsxs I FIG 3 POWER OPERATOR FOR A CONTROL VALVE BACKGROUND OF THE INVENTION Due to our increasing demands for petroleum products at locations remote from the petroleum source, and due to the increase in cost in transporting these petroleum products by rail or tankers, the use of pipe line facilities for moving petroleum products from the oil fields to remote locations for use have increased tremendously. A pipe line system includes a number of pumping stations for transferring the liquid material through the pipe line.

The prior art valve control mechanism for shutting down the pumping stations adjacent to the pumping means fail to.provide effective pressure control means and utilize excessive pwoer requirements to provide a controlled operation of the valve means.

In the past, the control liquid moving through a pipe line included a double seated equal percentage globe valve. The globevalve, however, has a disadvantage in that it consumes power even when fully opened (which is the normalcondition) since it has an inherent pressure drop. Usually it is sized for an initial full opened pressure drop of about 5 to p.s.i. to facilitate fast and stable control system response. This initial pressure drop can be a significant cost item on a large highcapacity liquid pipe line.

SUMMARY OF THE INVENTION The present invention basically includes a pair of hydraulic cylinder means, with one cylinder means being connected to one radially extending arm affixed to a valve control shaft and the other cylinder means being connected to a second arm extending from the valve control shaft. The radially extending arms and the hydraulic cylinder means are operatively associated with each other whereby one of the cylinders is operable at maximum leverage and is advanced to minimum leverage while the other hydraulic cylinder means is at minimum leverage and advances to maximum leverage.

The power operator for the control valve of the present invention includes a deceleration valve operatively associated with the position of a cam control element affixed to the valve control shaft. The cam control element and the deceleration valve are operatively associated with a hydraulic input into the two hydraulic cylinders for controlling the speed of adjustment of the valve control shaft in correspondence to the position of the valve.

The above described arrangement of the crank arms and pistons will provide a maximum rotation of the ball valve for a unit of control liquid when the ball valve is in a wide open position and less rotation of the ball valve for a unit of control liquid occurs as the ball valve approaches the closed position, thus creating a control system which gains reduction mechanically.

Another important feature of the present invention is the operative association of the crank arm means with the two hydraulic cylinder means whereby maximum lever means is provided during all positions of movement of the valve control shaft to thereby minimize the power required to effect rotary adjustment of the valve.

An additional important feature of the present invention' includes the provision of a stop pin which can be inserted in a test position relative to valve control shaft and crank arms to permit the control mechanism to be easily adjusted for speed of operation without closing the valve completely. A complete closing of a control valve during normal operation cannot be tolerated.

It is therefore a primary object of the present invention to provide a power operator for a control valve which can be utilized in a pipe line system for controlling'the pipe line pressure.

Yet another object of the present invention is to provide a deceleration control means which will vary the speed of adjustment of a valve element in response to the position of the valve element.

An additional object of the present invention is to provide a power operator for a control valve which is simple in construction, economical to manufacture and reliable in performance.

These and other advantages of the details of construction will become apparent upon reading the following description of the illustrative embodiment of a power operator control valve embodying the principles of the present invention, with reference to the attached drawings wherein like reference numerals have been used to refer to like parts throughout the several figures, and wherein:

BRIEF DESCRIPTION OF THE FIGURES OF DRAWING FIG. 1 is a vertical elevational view of a pipe line valve means including a power operator control means embodying the principles of the present invention,

with certain parts broken away and shown in section for purpose of clarity;

FIG. 2 is a horizontal sectional view taken along line 2-2 of FIG. 1;

FIG. 2A is a sectional view similar to FIG. 2 showing the power operator control means in an adjusted position.

FIG. 3 is a horizontal plan view taken along line 3-3 of FIG. 1;

FIG. 4 is an enlarged exploded perspective view of the power operator control means shown in FIG. 1, with certain parts omitted and certain parts broken away and shown in section for purpose of clarity; and,

FIG. 5 is a hydraulic schematic view of the control lines associated with the hydraulic cylinder means and deceleration valve.

DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENT Referring now to the drawing, the present invention will be described with reference to a control valve generally represented by the reference numeral 10 and a power operator assembly for the control valve generally represented by the reference numeral 40.

Thefunction of the control valve 10 is to provide means for effecting the opening and closing of a fluid pipe line adjacent pumping means, with the valve detailed to control pressure in the pipe line. The control valve is a ball valve having a valve housing 11. Valve housing 1 1 includes flanges 12, 14 which are connected by conventional means (not shown) to pipe line section 13, 15, respectively. Valve 10 includes a rotary ball valve element (not shown). The rotary ball valve element is operable between an open position to permit fluid to flow between pipe line sections 13 and 15 and a closed position to block the flow of fluid between pipe line sections 13, 15. The rotary ball valve element is rotated between the opened and closed positions by a valve control shaft 16. Valve control shaft 16 extends upwardly through a sleeve 17. Sleeve 17 includes a lower collar member 18 which is connected to an upper collar 19 of the valve housing 11. The upper extended end of sleeve 17 includes a support flange 20. The support flange 20 is fixed to sleeve 17 by conventional means such as welding and provides a-supporting surface for maintaining the power operator assembly 40 in position relative to the valve control shaft 16.

As shown in FIG. 4, the power operator assembly 40 includes a lower mounting plate 41. Mounting plate 41 is secured to the sleeve support flange 20 by conventional bolt connecting means 42.

As shown in FIG. 4, the valve control shaft 16 extends upwardly through an opening 43 in the lower mounting plate 41 and extends upwardly through an opening (not shown) in an upper mounting plate 44. Mounting plate 44 is detailed in shape and dimension similar to mounting plate'4l. The mounting plates 41, 44 are supported in substantially horizontally oriented vertically spaced parallel relationship and provide a space therebetween for supporting and housing the. valve actuating means, as will be described hereinbelow. The valve actuating means includes a pair of crank members 45, 46. Each of the crank members 45, 46 includes a pair of radially extending crank arms 47, 48. Crank arm 48 is slightly longer than crank arm 47. The crank arms 47, 48 are detailedin angular displacement relative to each other to define an obtuse angle of slightly greater than 90. Each of the crank members 45, 46 include openings 49, which are complementary to the outside surface of valve control shaft 16.

As shown in FIG. 4, the crank members 45, 46 are secured in an angularly set position relative to the valve control shaft 16 by means of a key element 50 which is provided on each of the crank arms 45, 46 and which is detailed in design to extend into a complementary key way 51 formed in valve control shaft 16. The crank member key elements 50 and control shaft key way 51 will cause angular movement of the crank members 45, 46 to effectcorresponding rotary movement of the valve control shaft 16, to thereby adjust the position of the rotary ball valve member located within the valve housing 11.

Angular movement of the crank members 45, 46 is effected by means of a pair of hydraulic control cylinder means 60, 61. The hydraulic control cylinder means 60 includes a conventional piston rod means 62 having an extended connecting collar 63. The connecting collar 63 is connected to the crank arms 48 by means of a pin means 64. Pin means 64 is inserted through openings provided in the crank arms and through an opening provided in the piston rod collar 63. Pin 64 is secured in a set position relative to the piston rod and crank arms by means of a retaining clip 65. As shown in FIG. 4, a pair of spacer elements 66 are provided on opposite sides of the piston rod collar member 63 and between the crank arms 48 to aid in effectively spacing the crank members 45, 46 axially relative to the valve control shaft 16. I

The hydraulic cylinder means 60 includes a base end 67 which is pivotally secured in a fixed position relative to the plate support' members 41, 44 by means of a connecting pin means 68. The connecting pin means 68 is inserted through a complementary opening provided in the plate 41, a complementary opening provided in the cylinder base 67 and a complementary opening provided in the plate support member 44. Pin 68 is held in a fixed position relative to the cylinder base end and support plates by means of a retaining clip 69. As shown in FIG. 4, a-pair of spacer elements 70 are provided on opposite sides of the cylinder base 67 and between the support plate members 41, 44. The hydraulic control cylinders 60 include a pair of hydraulic fluid input connecting members 71, 72. The hydraulic fluid connecting members 71, 72 will be described in more detail hereinbelow in regard to the operation of the power control assembly.

As shown in FIG. 4, the hydraulic cylinder means 61 includes a piston rod element 73. An extended end of piston rod element 73 is provided with a connecting collarmember 74. The connecting collar member 74 is secured to crank arms 47 by means of pin means 75. The pin means 75 is inserted through complementary openings in the crank arms 47 and through a complementary opening provided in the connecting collar 74. Pin 75 is secured in a set position by retaining clip 76. A pair of spacer elements 77 are provided on opposite sides of the piston rod connecting collar 74 and between the plate support members 41, 44. As shown in FIG. 4, the hydraulic cylinder 61 includes a base connecting member 78. Base connecting member 78 is pivotally secured in a fixed position relative to the plate members 41, 44 by means of a connecting pin 79. Connecting pin.79 is inserted through a complementary opening provided in plate member 41, a complementary opening provided in the base member 78 and a complementary opening provided in the plate support member 44. Pin 79 is secured inaset position relative to the plates 41, 44 by means of a retaining clip 80. A pair of spacer elements 81 are providedon opposite sides of the cylinder base connecting member 78 and between the plate support members 41, 44. The spacer members 66, 70,77 and 81 are journaled around their respective connecting pin and will provide suitable means for axially spacing the hydraulic cylinder means 60, 61 relative to the crank members 45, 46.

As shown in FIG. 4, the hydraulic cylinder means 61 includes a pair of hydraulic connecting members 82, 83. The hydraulic connecting members 82, 83 are adapted to be connected to the hydraulic control lines which will be described in more detail hereinbelow.

As shown in FIGS. 1, 3 and 4, the valve control shaft 16 extends upwardly to a position above support plate 44. The upper extended end of shaft 16 is provided with a rotary cam element 90. Rotary cam element includes a camming surface portion 91 which is operatively associated with a deceleration valve 92. The deceleration valve 92 includes a displaceable valve actuator element 93. Actuator element 93 is supported in abutting contact with the cam portion 91, whereby the rotary movement of cam element 90 will effect displacement of the valve actuator 93 to thereby control the flow of fluid through the valve 92. Valve 92 is a conventional two-way valve and includes an input supply line 94 and an output supply line 95. The fluid supply lines 94, 95 are adapted to be connected in series with the hydraulic system associated with the hydraulic cylinders 60, 61 to control the speed of actuation of the cylinder means 60, 61 as will be described in more detail hereinbelow in the description of the operation of the power operator control valve.

Referring now particularly to FIGS. 3 and 4, the power control assembly 40 embodying the principles of the present invention includes a limit stop pin means 100. Limit stop pin means 100 is adapted to be inserted through complementary openings 101, 102 provided in the plate support members 41, 42, respectively. The stop pin means 100 is detailed in location relative to the crank arms 48 whereby pivotal movement of the crank arms will contact the limit stop pin means 100 (as shown in dotted lines of FIGS. 2 and 2A) to permit easy adjustment for speed of operation of the control valve without closing the valve completely. The closing of a control valve associated with a pipe line system cannot be tolerated during normal operation. Therefore, the use of the stop pin means 100 will permit the desired adjustments to be made without completely closing the avove described ball valve mechanism 10.

O PERATION In utilizing the power operator for a control valve embodying the principles of thepresent invention, the power control assembly 40 is connected in operative association with a conventional ball valve 10 as described hereinabove. The control valve 100 and power control assembly 40 associated therewith are normally positioned on the discharge side of pump means associated with the pipe line and is operative to shut down or partially shut down the pipe line to control pressure in the pipe line.

As shown in FIG. 5, a conventional high pressure hydraulic supply means 110 having a pair of hydraulic control lines 111, 112 is hydraulically connected with the cylinders 60, 61 and deceleration valve 92. The hydraulic control line 111 includes an extended end which is connected to the fluid connecting element 82 of hydraulic cylinder 61 and includes branch linel13 which is connected to fluid connecting element 72 of hydraulic cylinder 60. Hydraulic control line 112 is connected to deceleration valve 92. Deceleration valve 92 is connected to a control line 114. Control line 114 is connected by a fluid flow connecting element 115 which is connected to fluid connecting element 71 of cylinder 60 and is connected by a control line 116 to the fluid connecting element 83 of hydraulic cylinder 61. The hydraulic supply means 110 is operable for furnishing a high pressure supply of fluid in alternate directions through the control lines 111, 112 and includes conventional actuator means (not shown) operable for initiating fluid flow through either of the control lines 111, 112.

The power operator control assembly shows the valve control mechanism in the open position in FIGS. 2 and 5. Operation of the power control assembly 40 to effect movement of the valve to a closed position (FIG. 2A) is effected by supplying high pressure fluid through the control line 111. High pressure fluid moving through control line 111 will be transferred through line extension into the extended end of hydraulic control cylinder 61. High pressure fluid moving into the extended end of hydraulic cylinder 61 will effect retraction of the piston rod 73 to thereby effect a counterclockwise rotation of the valve control shaft 16, as shown in FIGS. 2, 2A and 5. Simultaneously with the flow of high pressure fluid into the extended end of cylinders 61, the high. pressure fluid will flow throughv branch line 113 into the base end of cylinder 60. The flow of high pressure fluid into the base end of cylinder 60 will effect operation of cylinder 60 to force the piston rod 62 outwardly thereby aiding in the counterclockwise rotation of the valve control shaft 16. When hydraulic cylinder 61 is operated with the piston rod in the extended position, crank arms 47 will provide a maximum leverage at the beginning of the closing stroke of the control valve. A continued retraction of the hydraulic cylinders 61 will gradually reduce the leverage of crank arms 47. However, as the hydraulic cylinder 60 is expanded, the leverage on crank arms 48 will gradually increase until the crank arms reach a maximum leverage position. The above described increasing and decreasing leverage applied to crank arms 47, 48 will maintain optimum leverage on the control shaft 16 throughout the limit of angular movement, thus minimizing the power requirement for opening and closing the valve means 10.

Referring now particularly to FIG. 5, during retraction of the hydraulic cylinders 61, the hydraulic fluid exhausted from the cylinder will flow along supply line 116 through the connectable element 115, supply line 114, through deceleration valve 92, and control line 112 for return to the hydraulic supply source. Also, during expansion of the hydraulic cylinder 60, the fluid exhausted from the cylinder 60 will flow through the connectable element 1 15, supply line 1 l4, deceleration valve 92 and through the control line 112 for return to the hydraulic supply source 110.

As the exhausted hydraulic fluid flows through deceleration valve 92 for return to the supply source, the rate of flow of the exhausted fluidis controlled by the position of the rotary cam element 90. Since the rotary cam element 90 is fixed to the valve control shaft 16,

an angular displacement of shaft 16 will effect a corresponding angular displacement of the cam element 90. The cam element'camming surface 91 is detailed in design to decelerate the flow of fluid passing through the valve 92 as the valve approaches the fully closed position and vice versa to increase the rate of flow of fluid passing through valve 92 as the valve 10 moves away from the closed position and to again decrease the rate of flow as valve 10 approaches the fully open position. Thedeceleration valve 92 will control the rate at which the valve is moved between the open and closed conditions. In returning the control valve 10 to the open position, the hydraulic supply source will deliver the fluid under pressure to control line 112, valve 92 and supply lines 114, 116 to the hydraulic cylinders 60, 61 to reverse the direction of operation of the hydraulic cylinders, to thereby effect a clockwise rotation of the control shaft 16 for moving the valve 10 to the open position.

It now becomes apparent that the above described illustrative embodiments of a power operator for a control valve embodying the principles of the present invention is capable of obtaining the above stated objects and advantages.

What is claimed is:

1. A power operator for a control valve having a ro- -tatably displaceable control shaft, said power operator including crank means connected to said control shaft in such manner that angular movement of the crank means will effect corresponding rotary movement of the control shaft, said crank means including a pair of radially extending crank arms, with said crank arms being angularly displaced relative to each other, a pair of actuator means, one of said actuator means being operatively connected to each of said radially extending crank arms, said angular displacement of said crank arms and said operative association of said crank arms with said actuator means being such that one of said crank arms is operated from a maximum leverage to a minimum leverage while said other crank arm is moved from a minimum leverage to a maximum leverage, said actuator means including a pair of hydraulic cylinder means, and a deceleration valve means operatively associated with said hydraulic cylinder means for adjusting the speed of operation of said cylinder means be- .tween retracted and extended positions.

2. A power operator for a control valve as defined in claim I wherein said valve control shaft includes cam means operatively associated therewith for effecting adjustment of said decelerator valve means to thereby adjust the. speed of angular displacement of said valve control shaft in response to the position of said shaft.

3. A power operator for a control valve as defined in claim 2 and further characterized in that said cam means is detailed for decreasing the speed of angular displacement of said valve control shaft as said valve approaches a fully closedposition and is operable for increasing the speed of angular displacement of said valve control shaft as said valve moves away from said fully closed position and thereafter increasing the speed of angular displacement of said valve control shaft as said valve approaches said fully opened position.

4. A power operator for effecting adjustment of a control valve as defined in claim 3 and further characterized in that said crank arm means includes a pair of radially extending crank arms, with said crank arms detailed in angular displacement relative to each other to define an obtuse angle of approximately 90.

5. A power operator for effecting adjustment of a control valve as defined in claim 4 and further characterized in that said power operating means includes a pair of cylinder means having adjustable piston rod means, with one of said cylinder means being operatively connected to each of said radially extending crank arms, and wherein the angular displacement of said crank arms and said operative association of said crank arms with said cylinder means is detailed in operation whereby one of said crank arms is operated from a maximum leverage to a minimum leveragewhile said other crank arm is moved from a minimum leverage to a maximum leverage.

6. A power operator for effecting adjustment of a control valve as defined in claim 5 and further characterized in that said cylinder means includes hydraulic operating means and wherein said means for adjusting the speed of angular displacement of said valve control shaft includes a deceleration valve operatively associated with said hydraulic operating means, and wherein cam means is operatively associated with said valve control shaft and operatively associated with said deceleration valve for adjusting said valve in response to angular adjustment of said valve control shaft, to thereby adjust said'speed of angular displacement of said valve control shaft.

7. A power operator for effecting adjustment of a control valve as defined in claim 6 and further characterized in that said cam means is coaxially mounted relative to'said valve control shaft.

8. A power actuator for a control valve having open and closed positions and a rotatably displaceable control shaft, said power actuator comprising, in combination:

crank means connected to said control shaft for rotating such control shaft between valve-open and valve-closed positions, said crank means having a pair vof radial crank arms;

a pair of double acting piston-cylinder devices and support means therefor, each piston-cylinder device being pivotally connected at'one end to said support means and pivotally connected at its other end to a crank arm, one piston-cylinder device being connected to one of said crank arms and the other of said piston-cylinder devices being connected to the other of said crank arms and said piston-cylinder devices being disposed in generally side-by-side arrangement, said piston-cylinder devices being fluid-connected for cojoint push-pull operation and one of said piston-cylinder devices being essentially axially aligned with its crank arm when the crank means is in valve-closed position while the other. piston-cylinder device is positioned to exert substantially maximum leverage through its crank arm and vice versa when said crank means is in-valve-open position;

fluid pressure means connected to said pistoncylinder devices for actuating them simultaneously to move said crank means from valve-closed to valve-open position and from valve-open to valveclosedposition; and means operatively associated with said control shaft for adjusting the speed of angular displacement inparted to said crank means-by said piston-cylinder devices. 9. In a control valve having open and closed positions and having a valve control shaft rotatable through approximately-one fourth turn from its open to its closed position, a power operator for rotating said shaft from its open to its closed position and control means responsive to the angular position of said shaft for controlling the incremental speed at which said power operator rotates said shaft, said power operator including crank means connected to said shaft and a pair of piston-cylinder devices connected to said crankmeans, one of said devices being disposed to exert its minimum leverage in a prescribed direction while the other exerts its maximum leverage in that direction and vice versa, and hydraulic means for directing fluid to said devices for actuating said devices simultaneously.

10. The structure defined in claim 9 wherein said control means controls the flow of fluid to said devices.

11. A power operator for effecting adjustment of a control' valve between an open and closed position wherein said control valve includes a rotatable control shaft, said power operator including crank arm means fixed tosaid valve control shaft whereby angular displacement of said crank arms will effect corresponding conditions, said last-mentioned means including cam means operatively associated with said control valve shaft whereby angular displacement of said control valve shaft will cause said cam means to effect adjustment of said power operating means to thereby adjust said speed of angular displacement. 

1. A power operator for a control valve having a rotatably displaceable control shaft, said power operator including crank means connected to said control shaft in such manner that angular movement of the crank means will effect corresponding rotary movement of the control shaft, said crank means including a pair of radially extending crank arms, with said crank arms being angularly displaced relative to each other, a pair of actuator means, one of said actuator means being operatively connected to each of said radially extending crank arms, said angular displacement of said crank arms and said operative association of said crank arms with said actuator means being such that one of said crank arms is operated from a maximum leverage to a minimum leverage while said other crank arm is moved from a minimum leverage to a maximum leverage, said actuator means including a pair of hydraulic cylinder means, and a deceleration valve means operatively associated with said hydraulic cylinder means for adjusting the speed of operation of said cylinder means between retracted and extended positions.
 2. A power operator for a control valve as defined in claim 1 wherein said valve control shaft includes cam means operatively associated therewith for effecting adjustment of said decelerator valve means to thereby adjust the speed of angular displacement of said valve control shaft in response to the position of said shaft.
 3. A power operator for a control valve as defined in claim 2 and further characterized in that said cam means is detailed for decreasing the speed of angular displacement of said valve control shaft as said valve approaches a fully closed position and is operable for increasing the speed of angular displacement of said valve control shaft as said valve moves away from said fully closed position and therEafter increasing the speed of angular displacement of said valve control shaft as said valve approaches said fully opened position.
 4. A power operator for effecting adjustment of a control valve as defined in claim 3 and further characterized in that said crank arm means includes a pair of radially extending crank arms, with said crank arms detailed in angular displacement relative to each other to define an obtuse angle of approximately 90*.
 5. A power operator for effecting adjustment of a control valve as defined in claim 4 and further characterized in that said power operating means includes a pair of cylinder means having adjustable piston rod means, with one of said cylinder means being operatively connected to each of said radially extending crank arms, and wherein the angular displacement of said crank arms and said operative association of said crank arms with said cylinder means is detailed in operation whereby one of said crank arms is operated from a maximum leverage to a minimum leverage while said other crank arm is moved from a minimum leverage to a maximum leverage.
 6. A power operator for effecting adjustment of a control valve as defined in claim 5 and further characterized in that said cylinder means includes hydraulic operating means and wherein said means for adjusting the speed of angular displacement of said valve control shaft includes a deceleration valve operatively associated with said hydraulic operating means, and wherein cam means is operatively associated with said valve control shaft and operatively associated with said deceleration valve for adjusting said valve in response to angular adjustment of said valve control shaft, to thereby adjust said speed of angular displacement of said valve control shaft.
 7. A power operator for effecting adjustment of a control valve as defined in claim 6 and further characterized in that said cam means is coaxially mounted relative to said valve control shaft.
 8. A power actuator for a control valve having open and closed positions and a rotatably displaceable control shaft, said power actuator comprising, in combination: crank means connected to said control shaft for rotating such control shaft between valve-open and valve-closed positions, said crank means having a pair of radial crank arms; a pair of double acting piston-cylinder devices and support means therefor, each piston-cylinder device being pivotally connected at one end to said support means and pivotally connected at its other end to a crank arm, one piston-cylinder device being connected to one of said crank arms and the other of said piston-cylinder devices being connected to the other of said crank arms and said piston-cylinder devices being disposed in generally side-by-side arrangement, said piston-cylinder devices being fluid-connected for cojoint push-pull operation and one of said piston-cylinder devices being essentially axially aligned with its crank arm when the crank means is in valve-closed position while the other piston-cylinder device is positioned to exert substantially maximum leverage through its crank arm and vice versa when said crank means is in valve-open position; fluid pressure means connected to said piston-cylinder devices for actuating them simultaneously to move said crank means from valve-closed to valve-open position and from valve-open to valve-closed position; and means operatively associated with said control shaft for adjusting the speed of angular displacement inparted to said crank means by said piston-cylinder devices.
 9. In a control valve having open and closed positions and having a valve control shaft rotatable through approximately one fourth turn from its open to its closed position, a power operator for rotating said shaft from its open to its closed position and control means responsive to the angular position of said shaft for controlling the incremental speed at which said power operator rotates said shaft, said power operator including crank meAns connected to said shaft and a pair of piston-cylinder devices connected to said crank means, one of said devices being disposed to exert its minimum leverage in a prescribed direction while the other exerts its maximum leverage in that direction and vice versa, and hydraulic means for directing fluid to said devices for actuating said devices simultaneously.
 10. The structure defined in claim 9 wherein said control means controls the flow of fluid to said devices.
 11. A power operator for effecting adjustment of a control valve between an open and closed position wherein said control valve includes a rotatable control shaft, said power operator including crank arm means fixed to said valve control shaft whereby angular displacement of said crank arms will effect corresponding rotary movement of said valve control shaft, power operating means operatively connected to said crank arm means for effecting angular displacement of said crank arm means, and wherein means is operatively associated with the angular position of said valve control shaft for adjusting the speed of angular displacement of said valve control shaft between said open and closed conditions, said last-mentioned means including cam means operatively associated with said control valve shaft whereby angular displacement of said control valve shaft will cause said cam means to effect adjustment of said power operating means to thereby adjust said speed of angular displacement. 